Returning the first defined submatch with a given name when

there are multiple instances of the name.

lib/chibi/regexp.scm

@@ -102,8 +102,14 @@
   (vector-length (regexp-match-matches md)))
 
 (define (regexp-match-name-offset md name)
-  (cond ((assq name (regexp-match-names md)) => cdr)
-        (else (error "unknown match name" md name))))
+  (let lp ((ls (regexp-match-names md)) (first #f))
+    (cond
+     ((null? ls) (or first (error "unknown match name" md name)))
+     ((eq? name (caar ls))
+      (if (regexp-match-submatch-start+end md (cdar ls))
+          (cdar ls)
+          (lp (cdr ls) (or first (cdar ls)))))
+     (else (lp (cdr ls) first)))))
 
 (define (regexp-match-ref md n)
   (vector-ref (regexp-match-matches md)

tests/regexp-tests.scm

@@ -62,6 +62,16 @@
          '(: (* (*$ (or "ab" "cd"))) "c")
          "abcdc")
 
+(test "ab"
+    (regexp-match-submatch
+     (regexp-matches '(or (-> foo "ab") (-> foo "cd")) "ab")
+     'foo))
+
+(test "cd"
+    (regexp-match-submatch
+     (regexp-matches '(or (-> foo "ab") (-> foo "cd")) "cd")
+     'foo))
+
 (test-re '("ababc" "abab")
          '(: bos ($ (* "ab")) "c")
          "ababc")